Forget about worrying if the plot is plausible or implausible. You only need to focus on two words: John Noble. Before watching this show, I didn't know of John Noble, the Australian actor who plays the "mad" scientist, among other roles. He is simply a great, mesmerizing actor, full of wit, nuance, charm, heart and intelligence. He's also a very physical actor, able to "tell" his characters with wonderfully subtle gestures and expressions. I have watched the entire series through twice, and I don't think I will ever tire of his performance.
That being said, I also liked the rest of Fringe. The actors are all good, if not great. The story lines are generally good, with maybe a tad too heavy emphasis on icky skin eruptions during the first season. The arc story is fascinating. It does improve with age. I'm not a big fan of J.J. Abrams: the L.A.-style pretty people, the schmaltz, the xian savior themes that pop up out of nowhere, the obsession with broken father-son relationships. But here, it all feels a bit more real, and the obsessions are working for the show, not against it. One of my all-time faves, and for Orphan Black fans out there, definitely one of the precursors.